SINGAPORE - Prime Minister Lee Hsien Loong on Sunday thanked well-wishers for sending him their "concern, good wishes and encouraging words" after they learnt of his prostate cancer diagnosis.

Mr Lee will undergo surgery at Singapore General Hospital (SGH) on Monday to remove his prostate gland, and is expected to recover fully after that.

He was diagnosed with prostate cancer in January after a biopsy found cancer cells in one out of 38 samples taken from him. The Prime Minister's Office announced the diagnosis on Sunday.

"I have already received so many emails, SMSes, and messages through friends and contacts wishing me well," Mr Lee said in a Facebook post.

"I'm all set for my op tomorrow, and so are my surgeon and medical team."

He also posted a picture of himself in a hospital bed, holding up one of his fingers with a medical device attached to it. The device, a pulse oximeter, is used to track oxygen in a patient's bloodstream.

His wife Ho Ching, the chief executive officer of investment firm Temasek Holdings, helped him take the photo, he said.

"Here I am waking up in SGH after my earlier procedure last month - the prostate biopsy that detected the cancer," he said.

"Ho Ching helped me take this selfie of ET phoning home," he quipped, referring to the famous 1982 science-fiction film, E.T. the Extra-Terrestrial. The movie depicts an alien named E.T. who is stranded on Earth, and whose finger - said to have a healing touch - lights up.